title: Carbon monoxide signaling in human red blood cells: evidence for pentose phosphate pathway activation and protein deglutathionylation.
abstract: OBJECTIVE
  The biochemistry underlying the physiological, adaptive, and toxic effects of carbon monoxide (CO) is linked to its affinity for reduced transition metals. We investigated CO signaling in the vasculature, where hemoglobin (Hb), the CO most important metal-containing carrier is highly concentrated inside red blood cells (RBCs).
  
  
  RESULTS
  By combining NMR, MS, and spectrophotometric techniques, we found that CO treatment of whole blood increases the concentration of reduced glutathione (GSH) in RBC cytosol, which is linked to a significant Hb deglutathionylation. In addition, this process (i) does not activate glycolytic metabolism, (ii) boosts the pentose phosphate pathway (PPP), (iii) increases glutathione reductase activity, and (iv) decreases oxidized glutathione concentration. Moreover, GSH concentration was partially decreased in the presence of 2-deoxyglucose and the PPP antagonist dehydroepiandrosterone. Our MS results show for the first time that, besides Cys93, Hb glutathionylation occurs also at Cys112 of the β-chain, providing a new potential GSH source hitherto unknown.
  
  
  METHODS
  This work provides new insights on the signaling and antioxidant-boosting properties of CO in human blood, identifying Hb as a major source of GSH release and the PPP as a metabolic mechanism supporting Hb deglutathionylation.
  
  
  CONCLUSIONS
  CO-dependent GSH increase is a new RBC process linking a redox-inactive molecule, CO, to GSH redox signaling. This mechanism may be involved in the adaptive responses aimed to counteract stress conditions in mammalian tissues.
authors.affiliation: 1 Department of Cell Biology and Neurosciences, Sections of Biomarkers in Degenerative Diseases, Istituto Superiore di Sanità , Rome, Italy .
authors.forename: Alessio
authors.initials: A
authors.lastname: Metere
authors.forename: Egidio
authors.initials: E
authors.lastname: Iorio
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Scorza
authors.forename: Serena
authors.initials: S
authors.lastname: Camerini
authors.forename: Marialuisa
authors.initials: M
authors.lastname: Casella
authors.forename: Marco
authors.initials: M
authors.lastname: Crescenzi
authors.forename: Maurizio
authors.initials: M
authors.lastname: Minetti
authors.forename: Donatella
authors.initials: D
authors.lastname: Pietraforte
mesh_terms: D002248:Carbon Monoxide / Q000008:administration & dosage / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects; D004912:Erythrocytes / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D005978:Glutathione / Q000096:biosynthesis*; D019803:Glutathione Disulfide / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D018384:Oxidative Stress / Q000187:drug effects; D010427:Pentose Phosphate Pathway / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D006454:Hemoglobins; D002248:Carbon Monoxide; D005978:Glutathione; D019803:Glutathione Disulfide